8. The housing (410, 510, 610, 700, 800, 900) of claim 1, wherein the
curved path is defined by a single radius of curvature (RC), and
wherein the single radius of curvature (RC) is between 1 to 1000
inches.

11. The turbocharger (400, 500, 600) of claim 8, further comprising one or
more vanes (575) positioned in the diffuser (450, 550, 650, 750, 850,
950)

Description:

FIELD OF THE INVENTION

[0001]This invention is directed to a turbocharging system for an internal
combustion engine and more particularly to a diffuser of a turbocharging
system.

BACKGROUND OF THE INVENTION

[0002]Turbochargers are a type of forced induction system. They compress
the air flowing into an engine, thus boosting the engine's horsepower
without significantly increasing weight. Turbochargers use the exhaust
flow from the engine to spin a turbine, which in turn drives an air
compressor. Since the turbine spins about 30 times faster than most car
engines and it is hooked up to the exhaust, the temperature in the
turbine is very high. Additionally, due to the resulting high velocity of
flow, turbochargers are subjected to noise and vibration. Such conditions
can have a detrimental Affect on the components of the turbocharger,
particularly on the rotating parts such as the turbine rotor, which can
lead to failure of the system.

[0003]Turbochargers are widely used on internal combustion engines and, in
the past, have been particularly used with large diesel engines,
especially for highway trucks and marine applications. More recently, in
addition to use in connection with large diesel engines, turbochargers
have become popular for use in connection with smaller, passenger car
power plants. The use of a turbocharger in passenger car applications
permits selection of a power plant that develops the same amount of
horsepower from a smaller, lower mass engine. Using a lower mass engine
has the desired effect of decreasing the overall weight of the car,
increasing sporty performance, and enhancing fuel economy. Moreover, use
of a turbocharger permits more complete combustion of the fuel delivered
to the engine, thereby reducing the overall emissions of the engine,
which contributes to the highly desirable goal of a cleaner environment.
The design and function of turbochargers are described in detail in the
prior art, for example, U.S. Pat. Nos. 4,705,463, 5,399,064, and
6,164,931, the disclosures of which are incorporated herein by reference.

[0004]Turbocharger units typically include a turbine operatively connected
to the engine exhaust manifold, a compressor operatively connected to the
engine air intake manifold, and a shaft connecting the turbine and
compressor so that rotation of the turbine wheel causes rotation of the
compressor impeller. The turbine is driven to rotate by the exhaust gas
flowing in the exhaust manifold. The compressor impeller is driven to
rotate by the turbine, and, as it rotates, it increases the air mass flow
rate, airflow density and air pressure delivered to the engine cylinders.

[0005]As the use of turbochargers finds greater acceptance in passenger
car applications, three design criteria have moved to the forefront.
First, the market demands that all components of the power plant of
either a passenger car or truck, including the turbocharger, must provide
reliable operation for a much longer period than was demanded in the
past. That is, while it may have been acceptable in the past to require a
major engine overhaul after 80,000-100,000 miles for passenger cars, it
is now necessary to design engine components for reliable operation in
excess of 200,000 miles of operation. It is now necessary to design
engine components in trucks for reliable operation in excess of 1,000,000
miles of operation. This means that extra care must be taken to ensure
proper fabrication and cooperation of all supporting devices.

[0006]The second design criterion that has moved to the forefront is that
the power plant must meet or exceed very strict requirements in the area
of minimized NOx and particulate matter emissions. Third, with the
mass production of turbochargers, it is highly desirable to design a
turbocharger that meets the above criteria and is comprised of a minimum
number of parts. Further, those parts should be easy to manufacture and
easy to assemble, in order to provide a cost effective and reliable
turbocharger. Due to space within the engine compartment being scarce, it
is also desirable that the overall geometric package or envelope of the
turbocharger be minimized.

[0007]In Japanese Patent Application No. 2000257437A2 to Hiroyuki, a
compressor section for a turbocharger is shown which attempts to increase
the work load of the pressure conversion by elongating the diffuser. In
FIG. 1, an extended diffuser 22 is formed in a compressor housing 18
which is in communication with the compressor impeller 17, the impeller
chamber 21 and the scroll 23. The diffuser 22 has an elongated, straight
portion 22A extending from the inlet 25A of the diffuser. An end 22B
along the outlet portion 25B of the diffuser is bent to provide the fluid
communication between the scroll 23 and the diffuser 22.

[0008]The Hiroyuki system also suffers from the drawback of requiring a
large envelope to account for the length of the diffuser 22. The
increased envelope adds cost to the system by requiring more material to
be used, such as for compressor housing 18.

[0009]U.S. Pat. No. 6,679,057 to Arnold shows a turbocharger with a
compressor section having a compressor wheel and movable guide vanes. As
shown in FIG. 2, the Arnold system has a turbocharger 110 with a turbine
housing 112 adapted to receive exhaust gas from an internal combustion
engine and distribute the exhaust gas to an exhaust gas turbine wheel or
turbine 114 rotatably disposed within the turbine housing 112 and coupled
to one end of a common shaft 116. The turbine housing 112 encloses a
variable geometry system that comprises a plurality of pivotably moving
vanes 118. A turbine unison ring 119 engages the vanes 118 to effect
radially inward and outward movement thereof The turbine unison ring 119
comprises a plurality of slots 120 that correspond with tabs 122, and an
elliptical slot 123 that is configured to accommodate placement of an
actuator pin 124 therein for purposes of moving the unison ring. The pin
124 is attached to an actuator lever arm 126 and an actuator crank 128
which are disposed within a portion of the turbocharger center housing
130. The actuator crank 128 is rotatably disposed axially through the
turbocharger center housing 130, and is configured to move the lever arm
126 back and forth about an actuator crank longitudinal axis, which
movement operates to rotate the actuating pin 124 and effect rotation of
the unison ring 119 within the turbine housing.

[0010]The turbocharger 110 also comprises a compressor housing 131 that is
adapted to receive air from an air intake 132 and distribute the air to a
compressor impeller 134 rotatably disposed within the compressor housing
131 and coupled to an opposite end of the common shaft 116. The
compressor housing 131 also encloses a variable geometry member 136
interposed between the compressor impeller 134 and an air outlet. The
variable geometry member 136 is positioned in a straight, radial diffuser
175 and comprises a plurality of pivoting vanes 138. The diffuser 175 is
connected with volute 180, which is formed along an outer region and
radially remote from the impeller 134.

[0011]A compressor unison ring 140 is rotatably disposed within the
compressor housing 131 and is configured to engage and rotatably move all
of the compressor vanes 138 in unison. The compressor unison ring 140
comprises a plurality of slots 142 that correspond with tabs 144
projecting from each respective compressor vane. The compressor
adjustment ring 140 comprises a slot and an actuating pin 146 that is
rotatably disposed within the slot. An actuating lever arm 148 is
attached to the actuating pin 146 and to the actuator crank 128. The
actuating pin 146 and lever arm 148 are disposed through a backing plate
150 that is interposed between the turbocharger compressor housing 131
and the center housing 130. Rotation of the actuating pin 146 causes the
compressor unison ring 140 to rotate along the backing plate 150.

[0012]The Arnold system suffers from the drawback of requiring a large
envelope to account for the length of the diffuser 175 and the moveable
guide vanes 138 positioned therein. The increased envelope adds cost to
the system by requiring more material to be used, such as for the
compressor housing 131.

[0013]In FIG. 3, a portion of a contemporary compressor housing 200 is
shown having a scroll 220 and a flat radial diffuser 250. Diffuser 250
lies along diffuser plane PFD, which is formed along an outer
circumference of the scroll 220. To increase the diffuser length, the
contemporary turbocharger requires that the geometric envelope of the
turbocharger be increased. The increased envelope adds cost to the system
by requiring more material to be used, such as for a compressor housing.

[0014]Thus, there is a need for a turbocharger system, and method of
manufacturing such a system, that effectively and efficiently controls
fluid flow from the compressor wheel. There is a further need for such a
system that maximizes diffusion without increasing the size of the
geometric envelope. There is yet a further need for such a system and
method of manufacturing such a system that is reliable and
cost-effective.

SUMMARY OF THE INVENTION

[0015]The exemplary embodiments of the turbocharger diffuse fluid over a
desired length of a diffuser while maintaining the geometric package or
envelope. The diffuser can have a curved shape or other bend to maintain
the desired length for diffusing and/or to allow low momentum flow to
accelerate to a velocity substantially the same as the rest of the flow.
Increasing the length of the diffuser provides more and/or slower
diffusion of the fluid, which increases efficiency and/or stability in
compressing the fluid.

[0016]In one aspect of the invention, a housing for a turbocharger having
an impeller is provided. The housing comprises an impeller chamber
rotatably housing the impeller; a scroll; and a diffuser having an inlet
in proximity to the impeller and an outlet connected to the scroll. The
impeller chamber, diffuser and scroll are in fluid communication, and the
inlet has a curved shape.

[0017]In another aspect, a turbocharger is provided comprising an
impeller; and a housing defining an impeller chamber, a diffuser and a
scroll. The impeller is rotatably mounted in the housing. The impeller
chamber, diffuser and scroll are in fluid communication, and the diffuser
extends radially outward in a direction that is non-orthogonal to a
center line of the turbocharger.

[0018]In another aspect, a method of manufacturing a turbocharger is
provided. The method comprises providing a compressor housing having a
scroll, a diffuser and an impeller chamber in fluid communication with
each other; determining a velocity profile in the diffuser for fluid flow
driven by an impeller rotatably mounted in the compressor housing; and
forming a bend in the diffuser if the velocity profile is non-uniform.

[0019]The exemplary embodiments of the turbocharger diffuse fluid over a
sufficient length of a diffuser while providing a reduced geometric
package or envelope. The diffuser can have a curved shape or path to
maintain the sufficient length for diffusing and/or the inlet of the
diffuser can be radially outward of the inner circumference of the
scroll. The scroll can be moved closer to the impeller chamber while
positioned axially farther from the impeller to maintain the diffuser
length and take advantage of unused space within the geometric envelope.

[0020]In one aspect of the invention, a housing for a turbocharger having
an impeller is provided. The housing has a body rotatably housing the
impeller and defining an impeller chamber, a diffuser and a scroll. The
impeller chamber, diffuser and scroll are in fluid communication, and the
diffuser has a curved path or shape.

[0021]In another aspect, a turbocharger is provided comprising an
impeller; and a housing defining an impeller chamber, a diffuser and a
scroll. The impeller is rotatably mounted in the housing, and the
impeller chamber, diffuser and scroll are in fluid communication. The
diffuser has an inlet radially outward of an inner circumference of the
scroll.

[0022]In another aspect, a method of manufacturing a turbocharger is
provided. The method comprises faulting a compressor housing defining an
impeller chamber, a diffuser and a scroll; and rotatably mounting an
impeller in the compressor housing to compress and deliver a fluid
through the diffuser and scroll to an internal combustion engine. The
impeller chamber, diffuser and scroll are in fluid communication, and the
diffuser has a curved path.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]The present invention is illustrated by way of example and not
limitation in the accompanying drawings in which like reference numbers
indicate similar parts, and in which:

[0024]FIG. 1 is a schematic representation of a contemporary turbocharger
system with a diffuser;

[0025]FIG. 2 is a schematic representation of another contemporary
turbocharger system with a diffuser;

[0026]FIG. 3 is a schematic cross-sectional representation of a
contemporary radial flat diffuser;

[0027]FIG. 4 is a cross-sectional view of a portion of a turbocharger in
accordance with an exemplary embodiment of the invention;

[0028]FIG. 5 is a cross-sectional view of a portion of a turbocharger in
accordance with another exemplary embodiment of the invention;

[0029]FIG. 6A is a cross-sectional view of a portion of a turbocharger in
accordance with another exemplary embodiment of the invention;

[0030]FIG. 6B is an enlarged view of a portion of the turbocharger of FIG.
6 with an alternative compressor tip;

[0031]FIG. 6C is an enlarged view of a portion of the turbocharger of FIG.
6 with another alternative compressor tip;

[0032]FIG. 7 is a schematic cross-sectional representation of a
turbocharger housing in accordance with an exemplary embodiment of the
invention;

[0033]FIG. 8 is a schematic cross-sectional representation of a
turbocharger housing in accordance with another exemplary embodiment of
the invention;

[0034]FIG. 9 is a schematic cross-sectional representation of a
turbocharger housing in accordance with another exemplary embodiment of
the invention;

[0035]FIG. 10 is a cross-sectional view of a portion of a turbocharger in
accordance with an exemplary embodiment of the invention;

[0036]FIG. 11 is a graphical representation of performance data comparing
the turbocharger of FIG. 3 with a contemporary turbocharger having a
straight diffuser; and

[0037]FIG. 12 is another graphical representation of performance data
comparing the turbocharger of FIG. 10 with a contemporary turbocharger
having a straight diffuser.

DETAILED DESCRIPTION OF THE INVENTION

[0038]Embodiments of the invention are directed to diffusion in a
turbocharger for delivery of a compressed fluid to an internal combustion
engine. Aspects of the invention will be explained in connection with a
compressor section having a particular diffuser and scroll, but the
detailed description is intended only as exemplary. Exemplary embodiments
of the invention are shown in FIGS. 4-9, but the present invention is not
limited to the illustrated structure or application.

[0039]Referring to FIG. 4, a turbocharger 400 has a compressor housing 410
connected to center and turbine housings (not shown). The compressor
housing 410 has a compressor wheel or impeller 405 rotatably mounted
within an impeller chamber 403. The turbocharger 400 has various other
features which are not shown in FIG. 4, such as a turbine operatively
connected to the engine exhaust manifold, the compressor housing 410
being operatively connected to the engine air intake manifold, and a
shaft connecting the turbine impeller and compressor impeller 403 so that
rotation of the turbine impeller causes rotation of the compressor
impeller. The turbine impeller is driven to rotate by the exhaust gas
flowing in the exhaust manifold. The compressor impeller 405 is driven to
rotate by the turbine impeller, and, as it rotates, it increases the air
mass flow rate, airflow density and air pressure delivered to the engine
cylinders. Various other components and configurations can also be used
in turbocharger 400.

[0040]In the exemplary embodiment of turbocharger 400, the compressor
housing 410 has a volute with a scroll 420 and a diffuser 450 for fluid
communication between the impeller chamber 403 and the internal
combustion engine (not shown). An inlet 453 of the diffuser 450 is
preferably in proximity to a tip 408 of the compressor impeller 405. The
housing 410 can be formed of multiple portions, such as first and second
housings 411 and 412 connected by a connection mechanism 415, for
example, one or more bolts. The housing 410 can be formed by various
methods including casting, machining and a combination of casting and
machining. The housing 410 can be made of various materials including
aluminum.

[0041]The diffuser 450 can have a curved or otherwise non-linear shape. In
one embodiment, the diffuser 250 has a substantially smooth curvature,
such as defined by first and second radii of curvature RC1 and
RC2. While the exemplary embodiment of turbocharger 400 has the
curvature of diffuser 450 being defined by a pair of radii of curvature
RC1 and RC2, the present disclosure contemplates the diffuser
having other curved or non-linear shapes including being defined by a
single radius of curvature or more than two radii of curvature. The
present disclosure also contemplates one or more portions of the diffuser
450 being straight with the remaining portions being curved to provide a
non-linear shape for the diffuser.

[0042]The diffuser 450 has an outlet 458 that is connected to the scroll
420. Preferably, inlet 453 is provided with a bend or curved portion 455
that is in proximity to the compressor tip 408. The bend 455 allows for
low momentum flow from the compressor impeller 405 to be accelerated to
the same or a similar velocity as the reminder of the flow along the bend
providing stability to the fluid flow.

[0043]The curved or otherwise non-linear diffuser 450 allows for an
increase in the length of the diffuser without the need to increase the
geometric envelope for the turbocharger 400. The increased length of the
diffuser 450 provides for more diffusion and slower diffusion which will
increase efficiency and stability in the flow. To reduce losses along the
flow path of the diffuser 450, the curvature is preferably smooth without
any tight or sharp bends. In one embodiment, the walls of the diffuser
450 are angled, such as converging or diverging, to increase or decrease
the rate of diffusion.

[0044]Referring to FIG. 5, a turbocharger 500 has a compressor housing 510
with a compressor wheel or impeller 505 rotatably mounted within an
impeller chamber 503. Various components and configurations can be used
in turbocharger 500, such as those described above with respect to
turbocharger 400.

[0045]In the exemplary embodiment of turbocharger 500, the compressor
housing 510 has a volute with a scroll 520 and a diffuser 550 for fluid
communication between the impeller chamber 503 and the internal
combustion engine (not shown). An inlet 553 of the diffuser 550 is
preferably in proximity to a tip 508 of the compressor impeller 505. The
housing 510 can be formed of multiple portions, such as first and second
housings 511 and 512 connected by a connection mechanism 515, for
example, one or more bolts. The housing 510 can be formed by various
methods including casting, machining and a combination of casting and
machining. The housing 510 can be made of various materials including
aluminum.

[0046]The diffuser 550 can have a straight or linear shape which is at a
diffuser angle α with respect to the radial axis of the
turbocharger 500. In other words, the diffuser 550 can be non-orthogonal
to the center line CL of the turbocharger 500. The particular
diffuser angle α can be chosen based on a number of factors
including desired length of the diffuser 550, flow efficiency and desired
geometric envelope for the turbocharger 500. Diffuser angle α is
preferably between about 5 to 75 degrees, more preferably between about
10 to 60 degrees, and most preferably between 20 and 50 degrees. By
providing a substantially straight or linear diffuser 550, turbocharger
500 can reduce losses associated with bends, such as due to friction.

[0047]The diffuser 550 has an outlet 558 that is connected to the scroll
520. Due to diffuser angle α, the inlet 553 is provided with a
change of direction or bend that is in proximity to the compressor tip
508. The bend allows for low momentum flow from the compressor impeller
505 to be accelerated to the same or a similar velocity as the reminder
of the flow along the bend providing stability to the fluid flow.

[0048]The angled or non-orthogonal configuration of diffuser 550 allows
for an increase in the length of the diffuser without the need to
increase the geometric envelope for the turbocharger 500. The increased
length of the diffuser 550 provides for more diffusion and slower
diffusion which will increase efficiency. In one embodiment, the walls of
the diffuser 550 are angled, such as converging or diverging, to increase
or decrease the rate of diffusion.

[0049]Diffuser 550 can have one or more vanes 575. The vanes 575 can be
fixed or moveable. Where vanes 575 are moveable, appropriate actuating
mechanisms and techniques are used. The particular size, shape, and/or
configuration of the vanes 575 can be chosen based on a number of factors
including efficiency. The present disclosure also contemplates diffuser
550 being vaneless.

[0050]Referring to FIG. 6A, a turbocharger 600 has a compressor housing
610 with a compressor wheel or impeller 605 rotatably mounted within an
impeller chamber 603. Various components and configurations can be used
in turbocharger 600, such as those described above with respect to
turbocharger 400.

[0051]In the exemplary embodiment of turbocharger 600, the compressor
housing 610 has a volute with a scroll 620 and a diffuser 650 for fluid
communication between the impeller chamber 603 and the internal
combustion engine (not shown). An inlet 653 of the diffuser 650 is
preferably in proximity to a tip 608 of the compressor impeller 605. The
housing 610 can be formed of multiple portions, such as first and second
housings 611 and 612 connected by a connection mechanism 615, for
example, one or more bolts. The housing 610 can be formed by various
methods including casting, machining and a combination of casting and
machining. The housing 610 can be made of various materials including
aluminum.

[0052]The diffuser 650 can have a straight or linear shape which is at a
diffuser angle α a with respect to the radial axis of the
turbocharger 600. In other words, the diffuser 650 can be non-orthogonal
to the center line CL of the turbocharger 600. The particular diffuser
angle α can be chosen based on a number of factors including length
of the diffuser 650, flow efficiency and desired geometric envelope of
the turbocharger 600. Diffuser angle α is preferably between about
5 to 75 degrees, more preferably between about 10 to 60 degrees, and most
preferably between 20 and 50 degrees. By providing a substantially
straight or linear diffuser 650, turbocharger 600 can reduce losses
associated with bends, such as due to friction.

[0053]The embodiment of turbocharger 600 provides a diffuser 650 that
extends radially outward in a direction away from the turbine section
(not shown), where as the diffuser 550 of turbocharger 500 extends
radially outward in a direction towards the turbine section. Turbocharger
500 can take advantage of unused space in the geometric envelope in
proximity to the center housing (not shown), while turbocharger 600 can
take advantage of unused space in the geometric envelope in proximity to
the impeller chamber 603.

[0054]The diffuser 650 has an outlet 658 that is connected to the scroll
620. Due to diffuser angle α, the inlet 653 is provided with a
change of direction or bend that is in proximity to the compressor tip
608. The bend allows for low momentum flow from the compressor impeller
605 to be accelerated to the same or a similar velocity as the reminder
of the flow along the bend providing stability to the fluid flow.

[0055]The angled configuration of diffuser 650 allows for an increase in
the length of the diffuser without the need to increase the geometric
envelope for the turbocharger 600. The increased length of the diffuser
650 provides for more diffusion and slower diffusion which will increase
efficiency. In one embodiment, the walls of the diffuser 650 are angled,
such as converging or diverging, to increase or decrease the rate of
diffusion. Impeller 605 can have an extended tip 608 that extends into
the inlet 608.

[0056]Referring to FIG. 6B, an enlarged portion of turbocharger 600 is
shown with an axially flat or non-extended tip 609. The impeller 605
provides fluid entering the diffuser 650 with a non-uniform velocity
profile VP. The diffuser angle α and the bend or change of
direction in proximity to the inlet 653 allow for low momentum flow
FLM from the compressor impeller 605 to be accelerated to the same
or a similar velocity as the reminder of the flow along the bend. In one
embodiment, diffuser 650 is provided with a bend, change of direction or
other curvature immediately downstream of the impeller tip 609 to
accelerate the low momentum flow FLM to substantially the same
velocity as the remainder of the flow and stabilize flow. Downstream of
the rotor tip 609, the velocity profile VP is more uniform. In one
embodiment, the angle β can be changed to influence the velocity
profile. Changing the angle β can decrease the work or energy
required to turn the flow. Referring to FIG. 6C, an enlarged portion of
turbocharger 600 is shown with another axially flat or non-extended tip
609.

[0057]In one embodiment, a method of manufacturing turbochargers 400, 500
and 600 includes determining whether the fluid flow has a uniform or
non-uniform velocity profile VP at the inlet of the diffuser. If a
non-uniform velocity profile VP exists, then a bend or curvature is
formed in the diffuser in proximity to the diffuser inlet and preferably
immediately downstream of the inlet. The degree or extent of the bend or
curvature (e.g., the diffuser angle α or the radius of curvature)
is chosen based on the non-uniform velocity profile VP. For example,
a small diffuser angle α may be used with turbocharger 600 if it is
determined that there is only a small amount of non-uniformity in the
velocity profile VP such that the low momentum flow FLm only
requires a small amount of diffuser length in order to be accelerated to
substantially the same velocity as the remainder of the flow. A
correlation between the adjustment to the non-uniform velocity profile
VP and the degree or extent of the diffuser bend or curvature in
proximity to the inlet can be determined. However, the present disclosure
also contemplates the extent of the nonuniformity in the velocity profile
VP being one of several factors that are considered in determining
the degree or extent of the bend or curvature.

[0058]Referring to FIG. 7, a portion of a compressor housing 700 is shown
having a scroll 720 and a diffuser 750. Diffuser 750 lies along diffuser
plane PCD which intersects the scroll 720. The diffuser 750 has a
uniformly curved shape defined by a single radius of curvature RC.
The use of the uniformly curved diffuser 750 allows for a larger length
of the diffuser without the need to increase the geometric envelope for
the turbocharger. The longer diffuser length provides the advantages
described above with respect to turbochargers 400, 500 and 600.

[0059]Referring to FIG. 8, a portion of a compressor housing 800 is shown
having a scroll 820 and a diffuser 850. Diffuser 850 lies along diffuser
plane PRD which intersects the scroll 820. The diffuser 850
preferably has a uniformly curved shape defined by a single radius of
curvature RC. The use of the curved diffuser 850 allows for a larger
length of the diffuser without the need to increase the geometric
envelope for the turbocharger. The longer diffuser length provides the
advantages described above with respect to turbochargers 400, 500 and
600.

[0060]Housing 800 positions the scroll 820 outside of the curved diffuser
850 and reverses the direction of the flow after it enters the scroll
820, while maintaining substantially the same geometric envelope for the
turbocharger. Where the curve of diffuser 850 subtends an arc of 90
degrees, the diffuser plane PRD can bisect or pass through the
center of the scroll 820. In one embodiment, the walls can diverge to
increase the cross-sectional area, such as when the diffuser 850 turns
axially.

[0061]Referring to FIG. 9, a portion of a compressor housing 900 is shown
having a scroll 920 and a diffuser 950. Diffuser 950 lies along diffuser
plane PSD which is tangential to the scroll 920. The diffuser 950
preferably has a uniformly curved shape along a middle portion thereof
defined by the single radius of curvature RC. The use of the curved
diffuser 950 allows for a larger length of the diffuser without the need
to increase the geometric envelope for the turbocharger. The longer
diffuser length provides the advantages described above with respect to
turbochargers 400, 500 and 600.

[0062]Housing 900 increases the angle through which the diffuser 950
progresses before the entrance to the scroll 920. The direction of the
flow is reversed while still in the diffuser 950 and the diffuser length
is increased.

[0063]The exemplary embodiments produce a higher pressure ratio using
substantially the same geometric envelope as the contemporary compressor
housing. The exemplary embodiments also allow for flexibility in the
positioning of the scrolls and/or diffusers with respect to the other
components of the turbocharger, which is advantageous in smaller engine
compartments where space is at a premium. The diffusers described herein
can be vaneless or vaned, including fixed or moveable vanes.

[0064]Referring to FIG. 10, a turbocharger 1200 has a compressor housing
1210 connected to center and turbine housings (not shown). The compressor
housing 1210 has a compressor wheel or impeller 1220 rotatably mounted
within an impeller chamber 1230. The turbocharger 1200 has various other
features which are not shown in FIG. 3, such as a turbine operatively
connected to the engine exhaust manifold, the compressor housing 1210
being operatively connected to the engine air intake manifold, and a
shaft connecting the turbine impeller and compressor impeller 1220 so
that rotation of the turbine impeller causes rotation of the compressor
impeller. The turbine impeller is driven to rotate by the exhaust gas
flowing in the exhaust manifold. The compressor impeller 1220 is driven
to rotate by the turbine impeller, and, as it rotates, it increases the
air mass flow rate, airflow density and air pressure delivered to the
engine cylinders. Various other components and configurations can also be
used in turbocharger 1200.

[0065]In the exemplary embodiment of turbocharger 1200, the compressor
housing 1210 has a volute with a diffuser 1250 and a scroll 1260 for
fluid communication between the impeller chamber 1230 and the internal
combustion engine (not shown). An inlet 1255 of the diffuser 1250 is
preferably in proximity to a tip 1225 of the compressor impeller 1220.
The housing 1210 can be a single body or multiple portions, and can be
formed by various methods including casting, machining and a combination
of casting and machining. The housing 1210 can be made of various
materials including aluminum.

[0066]The diffuser 1250 can have a curved or otherwise non-linear shape or
path. In one embodiment, the diffuser 1250 has a substantially uniform
curvature, such as defined by a single radius of curvature RC. The
radius of curvature RC is preferably between about 1 to 1000 inches.
In another embodiment, the diffuser 1250 can include one or more guide
vanes 1400. The guide vanes 1400 can be fixed, moveable or a combination
of both.

[0067]While the exemplary embodiment of turbocharger 1200 shows the
curvature of diffuser 1250 being defined by a single radius of curvature
RC, the present disclosure contemplates the diffuser having other
curved or non-linear shapes including being defined by a plurality of
radii of curvature. The present disclosure also contemplates one or more
portions of the diffuser 1250 being straight with the remaining portions
being curved to provide a non-linear shape for the diffuser.

[0068]The diffuser 1250 has an outlet 1257 that is preferably connected to
the scroll 1260 along a radially outer portion (as measured from a
centerline CL of the turbocharger) of the scroll. Preferably, the
inlet 1255 of the diffuser 1250 is radially outward (as measured from the
centerline CL of the turbocharger) of the inner circumference of
scroll 260 as shown by reference line C. Where the tip 1225 of the
compressor impeller 1220 is in proximity to the diffuser inlet 1255, the
tip is also positioned radially outward of the inner circumference of the
scroll 1260.

[0069]The use of a curved or otherwise non-linear diffuser 1250 allows for
a smaller geometric envelope for the turbocharger 1200 without
sacrificing the length of the diffuser. As can be seen in FIG. 10, the
outer radius R, or the outer diameter, of the scroll 1260 can be reduced
to provide for the smaller geometric envelope or package while
maintaining the length over which the flow from the impeller 1220 is
permitted to diffuse.

[0070]The inlet 1255 of the diffuser 1250 is preferably axially remote
from the diffuser 1260 as shown by the separation of the scroll plane
PS and the inlet plane PI. By moving the scroll 1260 closer to
the impeller chamber 1230 but axially remote from the inlet 1255 of the
diffuser 1250 and/or from the impeller 1220, the turbocharger 1200
reduces the radial geometry of the envelope through utilization of unused
space in the envelope in an axial direction away from the impeller. There
is a greater amount of divergence in the region shown by arrow A as
compared to the region shown by arrow B. In one embodiment, the curvature
of the diffuser path is defined by a plurality of radii which can provide
more diffusion as compared to a path defined by a single radius of
curvature.

[0071]Referring to FIG. 11, the performance of turbocharger 1200 having
the curved diffuser 1250 and scroll 1260 was compared to a contemporary
turbocharger having a radially flat or straight diffuser. The curved
diffuser 1250 did not have any guide vanes. Turbocharger 1200 had a
scroll outer diameter that was 0.53 inches smaller than the scroll outer
diameter of the contemporary turbocharger having a radially flat or
straight diffuser. In a comparison of the pressure ratio with mass flow
rates, it was found that the pressure ratio performance of turbocharger
1200 was within acceptable limits as compared to the contemporary
turbocharger over various speed lines.

[0072]Referring to FIG. 5, the performance of turbocharger 1200 having the
curved diffuser 1260 and scroll 1260 was again compared to a contemporary
turbocharger having a radially flat or straight diffuser. The curved
diffuser 1250 did not have any guide vanes. Turbocharger 1200 had a
scroll outer diameter that was 0.53 inches smaller than the scroll outer
diameter of the contemporary turbocharger having a radially flat or
straight diffuser. In a comparison of the efficiency with mass flow
rates, it was found that the efficiency performance of turbocharger 1200
was within acceptable limits as compared to the contemporary turbocharger
over various speed lines, and exceeded the efficiency of the contemporary
turbocharger for a majority of the speed lines.

[0073]While the exemplary embodiment has been described with respect to a
compressor of a turbocharger, it should be understood that the present
disclosure contemplates the use of the exemplary embodiments with a
turbine of the turbocharger. The exemplary embodiment can also be used
with variable geometry guide vanes in either or both of the turbine and
compressor sections, as well as other types of turbochargers including
fixed vane turbochargers. It is also contemplated by the present
disclosure that the features of the turbochargers and/or housings can be
used with other types of fluid impelling devices where a particular
length of a diffuser is desired. Such other fluid impelling devices
include, but are not limited to, the following: superchargers;
centrifugal pumps; centrifugal fans; single-stage gas compressors;
multistage gas compressors; and other kinds of devices which generally
use one or more rotating elements to compress gases and/or induce fluid
flow.

[0074]While the invention has been described by reference to a specific
embodiment chosen for purposes of illustration, it should be apparent
that numerous modifications could be made thereto by those skilled in the
art without departing from the spirit and scope of the invention.